Count unique values in a double

I have a single column double with a lot of repeated values. I need to find the number of unique elements of that list (don't care about where they are) and also produce a list of all of the unique values.

When I've tried using unique() and diff() i get these errors.

>> count = unique(x(:,1))

Subscripting into a table using one subscript (as in t(i)) or three or more subscripts (as in t(i,j,k)) is not

supported. Always specify a row subscript and a variable subscript, as in t(rows,vars).

>> b = x([diff(x)~=0, false])

Error using horzcat

Dimensions of arrays being concatenated are not consistent.

Answer 1

[Walter Roberson]

The first error suggests that you might happen to have a table() object named unique in your workspace.

The second error tells you that x has at least three rows, so diff(x)~=0 has at least two rows; you cannot horzcat() a single false onto multiple rows.

By the way, when using logical indexing, you can omit all trailing false in the dimension. For example,

x = 1:5

x = 1×5

1 2 3 4 5

x([true false true false false])  %complete logical indexing

ans = 1×2

1 3

x([true false true])              %trailing false not needed

ans = 1×2

1 3

Answer 2

[Fangjun Jiang]

count = numel(unique(x(:,1)))

Answer 3

[Peter Perkins]

In addition to what Walter said, if you want the unique values of one variable in a table, likely this is what you should use:

count = unique(x.SomeVarName)

This

count = unique(x(:,1))

will return a shorter one-variable table. That's probably not what you want.